Continuous process for preparing alkanolamines

Abstract

A continuous process is provided for preparing alkanolamines having a high yield of monoalkanolamine, which comprises continuously reacting a flowing stream of a homogeneous mixture of an alkylene oxide having from two to four carbon atoms and ammonia in a molar ratio of ammonia to alkylene oxide within the range from about 15:1 to about 50:1 at temperatures above the critical temperature of the mixture and at pressures above the critical pressure of the mixture and maintaining the mixture in a single phase having a density of at least 15 lbs./cu.ft. for the time necessary to form an alkanolamine product mixture containing at least about 65% by weight monoalkanolamine.

What is claimed is: 
     
       1. A continuous process for preparing alkanolamines with high yields of monoalkanolamines, which comprises continuously reacting in a plug flow reactor a stream of a homogeneous mixture of an alkylene oxide having from two to four carbon atoms and ammonia in a molar ratio of ammonia to alkylene oxide within the range from about 15:1 to about 50:1 at temperatures above the critical temperature of the mixture and at pressures above the critical pressure of the mixture and maintaining the mixture in a single phase having a density of at least about 15 lbs./cu.ft. for the time necessary to form an alkanolamine product mixture containing at least about 65% by weight monoalkanolamine, said stream flowing in said reactor in a manner that minimizes back-mixing. 
     
     
       2. The process of claim 1 wherein said homogeneous mixture of reactants also contains a small catalytic amount of water. 
     
     
       3. The process of claim 1 wherein a swirling motion is imposed on the stream of reactants flowing through said reactor to avoid thermal stratification. 
     
     
       4. The process of claim 1 wherein unreacted ammonia is separated from the alkanolamine product mixture after completion of the reaction of the alkylene oxide. 
     
     
       5. The process of claim 4 wherein said separated unreacted ammonia is liquified and recycled for reaction with fresh amounts of alkylene oxide. 
     
     
       6. The process of claim 2 wherein a swirling motion is imposed on the stream of reactants flowing through said reactor to avoid thermal statification. 
     
     
       7. The process of claim 1 wherein the reaction is carried out under adiabatic conditions at a temperature of up to about 200° C. 
     
     
       8. The process of claim 2 wherein the reaction is carried out under adiabatic conditions at temperatures of up to about 200° C. 
     
     
       9. The process of claim 6 wherein the reaction is carried out under adiabatic conditions. 
     
     
       10. The process of claim 1 wherein the reaction is carried out at pressures in the range from about 170 atmospheres to about 240 atmospheres. 
     
     
       11. The process of claim 6 wherein the reaction is carried out at pressures in the range from about 170 atmospheres to about 240 atmosphere. 
     
     
       12. The process of claim 9 wherein the reaction is carried out at pressures in the range from about 170 atmospheres to about 240 atmospheres. 
     
     
       13. A continuous process for preparing alkanolamines with high yields of monoalkanolamines which comprises continuously reacting in a plug flow reactor a stream of a homogeneous mixture of an alkylene oxide having from two to four carbon atoms and ammonia in a molar ratio of ammonia to alkylene oxide within the range from about 15:1 to about 50:1 maintained in a single supercritical fluid phase having a density of at least 15 lbs./cu.ft. for the time necessary to form an alkanolamine product mixture containing predominately monoalkanolamine, said stream flowing in said reactor in a manner that minimizes backmixing.